The water vapor conductance rates (ĠH2O) of the Auca Mahuevo and Pinyes eggs are 341 and 3979 mg H2O/(dayTorr), respectively. These values support previous interpretations of egg burial for Pinyes clutches and open incubation (substantiated by trace fossil nests) for the much larger Auca Mahuevo titanosaur clutches. In addition, the potential ĠH2O of the titanosaur egg resembles that of some Late Cretaceous theropod eggs that are partially buried in sediment. The ĠH2O of Auca Mahuevo egg is 2.7 times greater than an avian egg of comparable size and the microenvironment of the nest remains unclear. Comparison of the fossil eggs to those of modern reptiles is difficult, due to the paucity of studies and broader range of values reported for reptile eggs. Detailed sedimentological studies are essential in order to distinguish biological features from those resulting from taphonomic or geologic phenomena. The taphonomic context and spatial association of fossil eggs provide an essential framework for comparisons of the reproductive biology of different dinosaur species, time periods, and paleogeographic regions.